Bariatric Surgery: A Key Role for Registered Dietitians

Abstract

Obesity is a complex disorder that impacts all organ systems. Individuals with obesity are at increased risk for a variety of comorbid conditions, including diabetes, hypertension, dyslipidemia, heart disease, sleep apnea, some types of cancer, nonalcoholic fatty liver disease, and osteoarthritis, among others. Those at highest risk are individuals with class III obesity (body mass index !40), a group that now includes almost 5% of all adults and more than 10% of all African-American adults in the United States (1). Nonsurgical approaches to the treatment of obesity, including lifestyle modification and pharmacotherapy, typically result in average weight losses of 5% to 10% of initial body weight. Importantly, losses of this magnitude can substantially improve existing comorbidities and prevent new weight-related conditions, including diabetes (2,3). However, studies suggest that most individuals with obesity hope to lose considerably more weight, often as much as 20% to 40% of initial body weight, and they may view lesser degrees of weight loss as a disappointment or even a failure (4,5). In addition, the physiologic adaptations to weight loss, including reductions in energy expenditure and changes in hungerand satiety-promoting hormones, make it more difficult for individuals to maintain a reduced body weight over time (6). As a result, successful weight management is an elusive goal for many patients with obesity who utilize nonsurgical therapies. The four articles presented in this issue of the Journal highlight the growing importance of surgical therapies in the care of patients with obesity and the role of registered dietitians (RDs) (7-10). Current bariatric surgical techniques include the two most common procedures, Roux-en-Y gastric bypass (RYGB) and laparoscopic adjustable gastric banding (LAGB), and several less common procedures, including laparoscopic sleeve gastrectomy (LSG) and biliopancreatic diversion with duodenal switch (BPD-DS). Potential mechanisms of action are shown in the Figure and include restriction of gastric capacity, modulation of gastrointestinal hormones that influence hunger and satiety, and induction of malabsorption (11-13). Beckman and colleagues provide a comprehensive literature review of one of these mechanisms, changes in gastrointestinal (GI) hormones that occur after the RYGB procedure (9). As stated in their review, “An understanding of how GI hormones change after RYGB may help dietitians to optimize nutrition care to this patient population” (9). Knowledge of gut hormones is also important to RDs because pharmaceutical companies have focused on the manipulation of these hormones as peripheral targets for appetite regulation (14). At this time, bariatric surgery is the most effective intervention for severe obesity, producing substantial weight loss (typically on the order of 30% to 70% of excess body weight) that is largely maintained over time (15). The benefits of bariatric surgery also include high rates of remission of many obesity-associated comorbidities, including diabetes, hypertension, and dyslipidemia, as well as an improvement in quality of life and a reduction in mortality rates (15,16). As a result of this success, the number of bariatric procedures done annually has increased dramatically in recent years, as noted in the accompanying review by Kulick and colleagues (7). In light of the increasing prevalence of severe obesity, this trend is likely to continue. RDs are accustomed to working in a team environment to provide care for patients with various disorders, including obesity. In fact, team practice for the treatment of obesity has become an established model of care. Hospital nutrition teams were initially established in the 1970s, shortly after the introduction of new technology for the invasive administration of specialized parenteral and enteral nutritional products. Typically comprised of an attending physician, RD, registered nurse, and pharmacist, these teams were established to provide safe delivery of optimal nutritional support while minimizing complications. The team-oriented, multidisciplinary approach to patient care was subsequently applied to the care of patients with diabetes, as exemplified in two landmark diabetes studies: the Diabetes Control and Complications Trial (17) and the Diabetes Prevention Program (2). Interdisciplinary teams are also an important component of the chronic care model (18). It is with this perspective that the team approach to obesity care has evolved (19). In 1991, the National Institutes of Health consensus report on Gastrointestinal Surgery for Severe Obesity recommended multidisciplinary teams with medical, surgical, psychiatric, and nutritional expertise (20). In the articles by Kulick and colleagues (7) and SnyderR. F. Kushner is a professor of medicine, Division of General Medicine, and L. M. Neff is an assistant professor of medicine, Division of Endocrinology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL. Address correspondence to: Robert F. Kushner, MD, 750 N Lake Shore Dr, Rubloff 9-976, Chicago, IL 60611. E-mail: rkushner@northwestern.edu Manuscript accepted: December 15, 2009. Copyright © 2010 by the American Dietetic Association. 0002-8223/10/11004-0002$36.00/0 doi: 10.1016/j.jada.2009.12.030